As part of the manufacturing process for making semiconductor devices, after sealing selected integrated circuits with resin, ceramic, or the like, it is conventional to subject the devices to various functional tests including a burn-in test to determine whether they are satisfactory or unsatisfactory products. Since a large number of semiconductor devices are handled in connection with such tests, a socket in which the devices can be easily inserted and removed is used, thereby making it possible to change the semiconductor devices, one after another in order to efficiently carrying out the testing. In view of the large number of packages and lead configurations of the semiconductor devices, the configuration of the sockets that are used vary accordingly.
Reference character 300 in FIG. 4a indicates a semiconductor device of the TSOP (thin small outline package) type. Numeral 102 in FIGS. 4b through 4d refers to a socket made according to the prior art often used in testing of such semiconductor devices. Socket 102 comprises a base 116, a cover 117 and an adaptor 115, all formed of electrically insulating material, and contact pins 120 formed of a copper alloy material. After cover 117 has been installed on base 116 in such a manner as to be vertically movable relative to the base, adaptor 115 is inserted into the recessed portion formed at the center of base 116 to provide a rectangular shaped seating portion 114 in socket 102. Section 109, comprising a plurality of slits or gaps 108, is arranged along the edges of two sides in the longitudinal direction of seating portion 114. Slits 108 are formed between partitions 107 that have been arranged equally spaced from one another along the two sides of base 116 with the top part of slits 108 being open. A contact pin 120 is arranged in each slit 108, shown in FIGS. 5a through 5c. Each contact pin 120 has a pedestal 121, a leg part 129 extending from the lower part of pedestal 121 and a flexible spring part 118 provided at the top of the contact pin. Contact pins 120 are inserted, one by one, from the top into each slit 108 prior to mounting cover 117 on base 116 with leg part 129 extending out of the bottom of base 116. Contact heads 122 and trigger portions 123 are provided at the tip of flexible spring part 118. When cover 117 is raised, contact heads 122 engage the surface of adapter 115 with a force provided by flexible spring parts 118. A spring 119 (FIG. 4d) is disposed between base 116 and cover 117 and a latch mechanism 111 (FIG. 4c) is provided on the base and the cover. Spring 119 urges cover 117 toward the raised position with its movement limited by latch mechanism 111. Trigger portions 123 of contact pins 120 are located outside of slits 108 and the distal tip parts 123a are out of engagement with cam member 113 formed in cover 117 when the cover is in the raised position (FIG. 5a).
When cover 117 is depressed in opposition to the spring force of spring 119, cam member 113 engages tip part 123a of trigger portion 123. When the cover is depressed further, cam member 113 moves downwardly while maintaining sliding engagement with tip parts 123a of trigger portions 123 and, as shown in FIG. 5b, the trigger parts 123 are forced outwardly. Concomitantly, flexible spring parts 118 are bent and contact heads 122 move outwardly and upwardly, away from the surface of adaptor 115, with a result that contact heads 122 are received in slits 108 as shown in FIG. 5b. When socket 102 is in the FIG. 5b position, a semiconductor device 300, held horizontally relative to socket 102 by a vacuum pick 310 with terminal leads 302 facing downwardly, can be dropped into the seating portion 114 through the opening at the center of cover 117. If the semiconductor device 300 is dropped straight down, the outer edges of package 301 engage platform member 104 on the surface of adaptor 115 and device 300 is thereby received on seating portion 114. If the downward force on the cover is released in this state, cover 117 is raised by the force of spring 119 with cam member 113 moving upwardly. Trigger portions 123 separate from cam member 113 with a result that the spring force of flexible part 118 causes contact head 122 to move from inside slits 108 downwardly and inwardly returning to their original state. When cover 117 has been completely raised, contact heads 122 engage respective terminal leads 302, as shown in FIG. 5d, thereby making it possible for an electrical test to be conducted. An enlarged view of the vicinity of a contact head 122 and a respective terminal lead 302 is shown in FIG. 6a. After completion of the test, cover 117 is pushed down and contact heads 122 are received in respective slits 108, thereby making it possible for the semiconductor device 300 to be removed (see FIG. 5e). An enlarged view of the vicinity of a terminal lead 302 at this stage is shown in FIG. 6b. When the top of semiconductor 300 is picked up by vacuum pack 310 and raised vertically, the semiconductor device can be removed from inside socket 102.
However, there are cases where a semiconductor device 300 is inserted askew or moves horizontally at the time of removal and can become entangled in section 109. Since the distance between the slits of socket 102, or the distance between the contact pins 120, is wider than the tip of a terminal lead 302 a terminal inserted askew or moved horizontally due to inaccurate positioning, can become caught in a slit 108 when the tip of a terminal lead 302 happens to engage slit section 109. Terminal leads of semiconductor devices have become thinner and thinner in recent years, with a result that such terminals tend to be easily bent by external forces thereby exacerbating the problem. In instances where the tip of the terminal lead 302 becomes entangled in a slit 108 and the terminal lead is bent, as described above, it then becomes impossible to reliably connect semiconductor device 300 to a printed substrate, thereby producing an unsatisfactory product. In view of the finer pitch of terminal leads, on the other hand, the accurate positioning of the terminal lead and the semiconductor device has become all the more critical.